Tiêu đề 13.AMINES _ DERIVATIVE COLOUR BOOKLET.pdf ✅

Chapter – 4   In organic compounds the important functional groups containing nitrogen are amino, cyano or nitrile, isocyanide & nitro groups.  Alkyl or aryl derivatives of ammonia are regarded as amines. These are obtained by replacing one or more hydrogen atoms by alkyl or aryl groups.  Amines are classified as primary, secondary or tertiary depending upon whether one, two or three atoms of hydrogen have been replaced by alkyl or aryl group  If amino group is attached with carbon then an amino compound, is formed if cyano or nitrile group is attached then cyanide or nitrile compounds, the isocyanides groups is attached then isocyanide compounds & if nitro group is attached then nitro compounds are made. NH3 CH3NH2 (CH3)2NH (CH3)3N Methylamine Dimethylamine Trimethylamine (10 –Primary) (20 –Secondary) (30 –Tertiary)  Thus, characteristic functional groups for 10 , 20 or 30 amines are: −NH2 (Primary); – NH (Secondary); – N – (Tertiary)  Amines are said to be ‘simple’ when all the alkyl or aryl groups are the same, & ‘mixed’ when they are different.  There is another class of compounds wherein all the four hydrogen atoms of an ammonium salt have been replaced by alkyl or aryl groups. such compounds are named as quaternary ammonium salts. [NH4] + X − [NR4] + X − Tetraalkylammonium halide AMINES INTRODUCTION 1 Nitrogen Containing Compounds Amines RNH2(10 ); R2NH (20 ); R3N (30 ) Nitro compounds RNO2; ArNO2 Cyanides RCN Isocyanides RNC Nitrites RONO Diazonium Salts ArN2 +X − −H/+CH3 −H/+CH3 −H/+CH3 −4H/+4R  Like ammonia, nitrogen atom of amines is trivalent & carries an unshared pair of electrons.  Nitrogen orbitals in amines are therefore sp3 hybridised & the geometry of amines is pyramidal.  Each of the three sp3 hybridised orbitals of nitrogen overlap with orbitals of hydrogen or carbon depending upon the composition of the amines. The fourth orbital of nitrogen in all amines contains an unshared pair of electrons.  Due to the presence of unshared pair of electrons, the angle C – N – E. (where E is C or H) is less than 109.50 ; for instance, it is 1080 in case of Trimethylamine. Non-bonding (unshared) electron pair CH3 CH3 CH3 STRUCTURE 2 1080 0